This invention generally relates to antenna structures and antenna assemblies used with wireless communication apparatus and including a method of fabricating an antenna structure.
Antenna structures or assemblies have been used in wireless communication equipment such as in the radio telephone art, personal base stations, portable handsets and other communication terminals which are small, compact and lightweight. Considerable efforts have been made to fabricate such antennas in an efficient manner, particularly when the antennas are used with miniaturized electronic and radio frequency circuitry, but such efforts continue to be plagued with cost, fabrication and use problems.
For instance, some antennas are stamped and formed of sheet metal material, with selected contact portions being plated with precious metal. This stamping is quite flexible and rather xe2x80x9cflimsyxe2x80x9d. Consequently, a separate rigid base structure of dielectric material, such as molded plastic, is provided for attaching the stamped and formed antenna thereto. The separate base structure typically has some form of mounting means for mounting the assembly on another structure such as a printed circuit board. The separate stamping and separate molding processes are unduly expensive, particularly in automated processes. In addition, it is difficult to maintain true tolerances, and this causes connection problems if the stamped antenna is to be electrically connected to a printed circuit board.
In order to avoid the tolerance problems of the stamped and formed antennas as described above, other antennas have also been made by a two-shot molding process which involves molding the dielectric base structure with two different plastic materials. Specifically, a mounting portion of the base structure is molded of a plastic material which can be utilized for mounting on another structure such as a printed circuit board. This first material typically is not plateable. A second plateable plastic portion then is molded over the first portion. Selective areas of the second, plateable plastic portion then are plated with metal antenna material in an electroless plating process. Although this type of antenna has better tolerances than the stamped antennas described above, this two-shot molding and selective plating procedure is quite expensive, involving expensive tooling, multiple processes and materials.
The present invention is directed to solving these various problems of prior art antennas and methods of fabrication as described above, and to provide an improved antenna structure and assembly along with a new more robust method of fabricating the same.
A general object, of the present invention is to provide a new and improved antenna structure of the character described.
Another object of the present invention is to provide an inexpensive dual band antenna for use in wireless handsets, portable computers and other electronic devices.
A further object of the invention is to provide a new and improved method of fabricating an antenna structure.
In the exemplary embodiment of the invention, an antenna structure includes a dielectric plastic core configured in the desired shape of the antenna structure. A conductive metal plating is applied over substantially the entire dielectric plastic core.
The invention contemplates attaching the above antenna structure to a dielectric base structure which is adapted for mounting on an appropriate support, substrate or the like, such as a printed circuit board. Specifically, complementary interengaging attachment means are provided between the base structure and the antenna structure to secure the antenna structure on the base structure.
As disclosed herein, the plated dielectric plastic core may be substantially planar in configuration. According to one aspect of the invention, the complementary interengaging attachment means between the base and antenna structures is provided by at least one attachment post on the base structure press-fit into an attachment hole in the antenna structure. According to another aspect of the invention, the base structure is molded of plastic material, and the complementary interengaging attachment means include portions of the base structure overmolded about portions of the antenna structure.
As disclosed herein, the base structure is adapted for mounting on a printed circuit board. A feature of the invention comprises a conductive contact clip interengaged between the antenna structure and the circuit board. The conductive contact clip is provided by a metal spring clip mounted on an arm of the antenna structure. The arm extends over the base structure toward the printed circuit board.
The method of fabricating the antenna structure according to the invention includes plating the molded plastic core by an electroplating process. The method also contemplates molding a plurality of the plastic cores in a multi-core array joined by an integrally molded carrier structure. The cores subsequently are severed from the carrier structure. The cores may be gang plated prior to being severed from the carrier structure, or the cores may be individually plated after severance.
Other objects, features and advantages of the invention will be apparent from the following detailed description taken in connection with the accompanying drawings.